At he death of Valentinian I in AD 375, Gratian took control of the empire. To appease the Danubian legions who had an intense rivalry with those on the Rhine, Gratian appointed his four-year-old half-brother Valentinian II as co-emperor. Gratian knew his young brother was innocent of any wrongdoing and did not feel threatened by this arrangement. A crisis was averted. When Valens was killed at the battle of Adrianople, Valentinian II was still very young. In fact, even when Gratian was killed while confronting the usurper Magnus Maximus in Britain, he was only eight years old. Magnus Maximus controlled all of the western empire except for the areas of Italiae, Africa, and Pannoniae. Later, however, Maximus decided to expand his reign and moved on the young emperor. Valentinian II and his mother fled to the eastern empire to seek protection with emperor Theodosius I. Theodosius eventually led a campaign against Maximus and had the usurper executed; Valentinian II was reinstated in title only since the real power was unquestionably Theodosiusí. In AD 391, Theodosius left Italy to return east. He left control of the west to Valentinian II under the supervision of Arbogast, Frankish 'Master of the Soldiers', who began his move for power (unbeknownst to Theodosius). In AD 392, Valentinian II dismissed Arbogast as his advisor, but the arrogant man insolently threw the dismissal document at the emperorís feet. Not very long thereafter on May 15 of the same year, Valentinian II was found hanging by the neck in his palace at Vienna. Some claim suicide, but others cry foul play. The emperor was merely twenty one when he breathed his last.